Now although those algal blooms might be kind of positive, I mean they are providing a food source, they are the basis of the food chain. Some algal blooms are toxic, directly toxic, meaning that any organisms that ingest the blooms or are swimming in the blooms can get poisoned and die. In this picture this is a wild boar. The wild boar was probably eating some of this algae that was on the beach, but this happened to be a toxic algae. So this can be really detrimental to that ecosystem. And this can also make humans sick. Now, you’re probably not eating this algae, but if you’re gonna be swimming in that water there’s quite a bit of toxins in the water as well. So definitely pay attention to the news before going to the beach if they say there’s some sort of algal bloom out there. The other way algal blooms can be negative has to do with all algal blooms, no matter if they’re toxic or regular. And tt’s actually not the algae itself, it’s what happens when the algae die. Now remember, we’re giving them fertilizer. It rained and a whole bunch of fertilizer entered that aquatic ecosystem. And now we have a whole whole bunch of algae. Well, eventually you’re gonna run out of nutrients. All of those algae are gonna use all that nitrogen and all that phosphorous and all that potassium, and there’s gonna be no more nutrients left. So eventually that algae is going to start dying. Now when this happens, remember our decomposers when we’re talking about ecosystem roles. Our decomposers are going to start eating that algae. It’s a perfect resource for decomposers. Well, there’s a whole bunch of dead algae meaning there’s probably going to be a whole bunch of decomposers. And those decomposers are going to start eating. They’re gonna start breaking down that algae, which uses a lot of oxygen. Remember, our decomposers are doing cellular respiration. And as a review, hopefully you haven’t completely forgotten what that is that is. Food such as glucose plus oxygen makes ATP, carbon dioxide, and water. So these decomposers are breaking down algae. They’re eating food, so that means they need a lot of oxygen in order to break down that food. So this is a picture kind of showing, you know, here is an ecosystem. Here is that algal bloom, and we’ve got all these nice nutrients coming in feeding that algae bloom. But eventually the algae bloom starts dying and you have bacteria and other decomposers that are gonna start breaking it down and using up this oxygen, which is going to result in oxygen depletion. So there’s going to be so many decomposers around that they’re gonna use literally all the oxygen that is in that water. So this is kind of a picture of that. In this case, what happens when all that oxygen gets used, it’s going to cause something called a dead zone. So in this part of both of these pictures these are thousands, maybe even millions of fish that are dead. They literally suffocated. It’s weird thinking that fish suffocate because they swim. But fish actually get oxygen out of the water and when oxygen is too low they don’t have any oxygen and they suffocate, which is really really interesting, but also really really bad. Not only is this bad for people like us because maybe we wanted to eat those fish, but you just lost a whole food resource in the ecosystem. Now these conditions, the conditions without having oxygen, is referred to as hypoxia or anoxia. Hypoxia just means low oxygen, whereas anoxia means no oxygen. Remember abiotic resources the A represented not? That’s a way to remember anoxia, this A is representing not. There’s no oxygen in this ecosystem. Even if you’re in a hypoxic zone where there’s low oxygen, if it’s too low these fish could still suffocate. And again, this wasn’t caused directly by algae, it was caused really by the decomposers breaking down that algae. Now the United States is kind of familiar with dead zones. We have a huge dead zone that occurs every year in the Gulf of Mexico. It usually happens late in the summer, so you’re looking August, September, maybe into the beginning of October in the Gulf of Mexico. And the reason this happens in the Gulf of Mexico, is we’ve got a nice river all the way here. Hopefully you know which river this is. This is the Mississippi River. And on the Mississippi River, there’s tons of other rivers that drain into it, so all the colored areas of this map are all areas where if you were to drop a cup of water, eventually that water would land in the Mississippi River. So as you can see, like maybe a good third, maybe a little over a third, of the United States is actually a floodplain or watershed for the Mississippi River. Now if you know much about agriculture in the United States, you may know that a lot of our agriculture is right here in the middle of the United States. So we have all these huge industrialized mega farms that are growing corn, growing wheat, growing oats, growing everything. They’re using lots of fertilizer. It rains and that fertilizer runs off and it ends up in the Mississippi River, and eventually all those nutrients get carried down and down into the Gulf of Mexico. Now the reason this is particularly bad in the late summer and early fall is 1: that’s when a lot of our crops are active. But 2: you’re also starting to get more rain, so again, more rain, more runoff, more nutrients, more algal blooms, more algal blooms dying, more hypoxia. And that’s a really good kind of series of events that you should know because that you could definitely see that on a test, for example. Now this dead zone is getting worse. So in 2017, so this year, this was the largest dead zone ever recorded in the Gulf of Mexico. So here, this is Louisiana right along here, and them here we’ve got Texas, and then here we have the Gulf of Mexico. Now to give you an idea of how large this area is, this is about the size of New Jersey. Okay, this is insane. Now the different colors are representing the different levels of oxygen. Red is pretty close to anoxic. Currently it says just less than 2 so 0 would be anoxic. So some of this might be 0 or 1 or 2. The yellow, so this part right here, this is fine. This is part that they measured and it’s like oh it’s bigger than 5. 5 is kind of normal. So these are kind of okay areas. But everywhere in orange and red are lower than necessary levels. 5 milligrams per liter of oxygen is kind of the bare minimum fish need to survive. Now this doesn’t always cause a fish kill like we saw before. You know, if fish like live like right here, they’re gonna swim over there. But let’s say you’re stuck along the coast. Any direction you go in, you’re hitting a dead zone, and that’s when you start seeing those really big kill offs of fish. This really affects the shrimp and shellfish fishery every year down here because shrimp can’t really move that far. Yes, they do swim, but they can’t swim, you know, the width of New Jersey away like our larger fish can. So causes really big economic problems every year and unfortunately it’s getting worse. Fortunately, not so much for the Gulf of Mexico, but for the Chesapeake Bay, our lawmakers saw this happening in the Chesapeake Bay, and they actually put tons and tons of regulations on farms in order to limit the amount of nutrients that were being washed away. So what can we do? I mean, it sounds like doom and gloom and there’s some bad things happening, and there are, bu it’s not the end-all be-all. So one thing that both we and farmers can do, because we use fertilizer too. Think of your lawns, think of golf courses, especially. Schoolyards, parks, we use fertilizer as well. First, use less. You know, more isn’t necessarily better. Plants can only take up but so much nutrients. If you put a whole bag of fertilizer on a plant, the plant can’t take in all of that fertilizer. So just use less. You may be using way more than you think you need. Related to use less, use specifically. Get your soil tested. Whether you’re a farmer or whether this is your backyard, figure out what nutrients are missing in your soil. If you’re missing a lot of nitrogen, then get a fertilizer with a lot of nitrogen, but not so much phosphorus and potassium. And then also time with the rain. If it’s going to rain tomorrow, don’t fertilize your lawn today. If it’s not gonna rain till next week, then you’re more in the clear. This is also beneficial to you and, you know, the farmer, because if it rains and it washes away, all that means is you have to re-fertilize your plants and your plants barely got to use that fertilizer. So it’s almost like wasted fertilizer. Another solution is changing the type of fertilizer you’re using. So the bags earlier that I showed you that said NPK, those would be considered chemical fertilizers or synthetic fertilizers. Those were made in a lab somewhere or a factory somewhere. And that’s not necessarily bad. There’s no harmful chemicals in there, but they’re not natural. Earth doesn’t know how to really process those as efficiently. Which is fine, but there’s something we can do. Instead of using a commercial fertilizer, which is really fast acting because it’s the perfect nitrogen, phosphorus, potassium the plants need, but the thing is that it leeches out of the soil pretty easily. It doesn’t stay in the soil. Instead, compost does. And you’ve probably heard of composting. It’s becoming a bigger and bigger thing in the United States. Compost is just dead stuff. Dead, I say dead stuff, but stuff we don’t use. So the parts of vegetables and fruits you don’t eat. Eggshells, coffee grounds, dead leaves, dead grass. It’s all of these things that were alive and we just kind of put it all together in soil and let it break down over time. And that’s the thing, it breaks down over time. Meaning it releases nutrients over time. So if you’re putting compost down, 1: it is kind of a soil and that soil is not really gonna wash away. The plants are gonna keep it in place. And because it’s slowly releasing nutrients, it’s helping those crops out in the long run. This is especially good. Especially if you’re thinking about your own garden. You know, you are eating vegetables and have scraps all the time. Well just recycle those scraps. It helps your plant out, you don’t have to use commercial fertilizers, and you don’t really have to worry about runoff. So a really awesome solution to this problem. So as a review, again, there’s two major types of agriculture. We have the industrialized agriculture, which is typically a monoculture, and the traditional subsistence agriculture, which is typically a polyculture. One of the things that we use in our agriculture are fertilizers, but fertilizers can run off. And when they run off, they can cause those algal blooms, which eventually will die. And once they start dying, decomposition takes place and sucks out all of the oxygen. But have no fear, there are ways to fix this by timing our use of fertilizer, using an appropriate amount, and even switching to a more organic or a compost type fertilizer.